Authorities in Chicago say a thrift store employee was killed this morning after a gun hidden inside of donated clothing discharged, sending a bullet into her chest.

NBC Chicago reports that the victim, a 54-year-old woman, was sorting through clothes with a co-worker at the South Side Washington Heights thrift store. When the woman shook a sock, a gun reportedly fell out, firing as it hit the floor and sending a bullet into her chest.

The woman was rushed to Advocate Christ Medical Center, but was pronounced dead at 10:47 a.m. Her identity has not been released to the public due to pending family notification, but NBC Chicago mentioned that detectives are investigating the incident.